The number of cases of human diarrhea attributed to Cryptosporidium parvum has increased dramatically in the last decade. In immunocompromised individuals, most notably AIDS patients, cryptosproridiosis can present as a fulminant and persistent diarrhea. There is currently no known chemotherapeutic agent that is effective against this coccidian parasite. As a result, the mortality rate for cryptosporidiosis in AIDS patients exceeds 60 percent. As the number of immunocompromised persons increases, so does the need for an effective therapy. Two independent groups have produced hyperimmune bovine anti-C. parvum colostrum which has been successful in the treatment of at least five cases of human cryptosporidiosis. There are, however, conflicting reports in the literature regarding the prophylactic and therapeutic properties of various colostrum preparations. This proposal will examine the therapeutic effects of immunoglobulin and non-immunoglobulin fractions prepared from colostrum with demonstrated efficacy in human and animal infections. Methods will also be examined for improved and expanded production of therapeutic colostrum.